(1) Field of the Invention
The present invention relates to a ceramic orthodontic bracket having a good transparency and unobtrusive color, and a process for making the same.
(2) Description of the Related Art
As the material of an orthodontic bracket, stainless steel and plastic materials such as polycarbonate have been used. Furthermore, alumina ceramic materials have been recently used.
Stainless steel has been generally used for orthodontic brackets. Stainless steel has an excellent strength and machinability, but since it has a metallic luster, when a stainless steel orthodontic bracket is attached to a row of teeth, the bracket stands out conspicuously and spoils the appearance of the patient. From the viewpoint of eliminating this defect of spoilage of the appearance, a transparent plastic bracket is sometimes used. But this plastic bracket has a problem such that slip between the bracket and an orthodontic wire is poor and a satisfactory orthodontic effect cannot be attained. An alumina ceramic bracket has excellent rigidity and a good slip between the bracket and wire, but since the transparency is poor, when the bracket is set in the mouth, the problem of the visible soilage of the brackets still arises.